linux-kernel - [PATCH AUTOSEL 5.10 09/14] Revert "xen-netback: remove 'hotplug-status' once it has served its purpose"

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Message-Id: <20220301201833.18841-9-sashal@kernel.org>
Date:   Tue,  1 Mar 2022 15:18:21 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>, Paul Durrant <paul@....org>,
        Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>, wei.liu@...nel.org,
        davem@...emloft.net, xen-devel@...ts.xenproject.org,
        netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.10 09/14] Revert "xen-netback: remove 'hotplug-status' once it has served its purpose"

From: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.com>

[ Upstream commit 0f4558ae91870692ce7f509c31c9d6ee721d8cdc ]

This reverts commit 1f2565780e9b7218cf92c7630130e82dcc0fe9c2.

The 'hotplug-status' node should not be removed as long as the vif
device remains configured. Otherwise the xen-netback would wait for
re-running the network script even if it was already called (in case of
the frontent re-connecting). But also, it _should_ be removed when the
vif device is destroyed (for example when unbinding the driver) -
otherwise hotplug script would not configure the device whenever it
re-appear.

Moving removal of the 'hotplug-status' node was a workaround for nothing
calling network script after xen-netback module is reloaded. But when
vif interface is re-created (on xen-netback unbind/bind for example),
the script should be called, regardless of who does that - currently
this case is not handled by the toolstack, and requires manual
script call. Keeping hotplug-status=connected to skip the call is wrong
and leads to not configured interface.

More discussion at
https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe.org/T/#u

Signed-off-by: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.com>
Reviewed-by: Paul Durrant <paul@....org>
Link: https://lore.kernel.org/r/20220222001817.2264967-1-marmarek@invisiblethingslab.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/xen-netback/xenbus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 94d19158efc18..7acf3940dc1ff 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -256,6 +256,7 @@ static void backend_disconnect(struct backend_info *be)
 		unsigned int queue_index;

 		xen_unregister_watchers(vif);
+		xenbus_rm(XBT_NIL, be->dev->nodename, "hotplug-status");
 #ifdef CONFIG_DEBUG_FS
 		xenvif_debugfs_delif(vif);
 #endif /* CONFIG_DEBUG_FS */
@@ -675,7 +676,6 @@ static void hotplug_status_changed(struct xenbus_watch *watch,

 		/* Not interested in this watch anymore. */
 		unregister_hotplug_status_watch(be);
-		xenbus_rm(XBT_NIL, be->dev->nodename, "hotplug-status");
 	}
 	kfree(str);
 }
-- 
2.34.1